The Staffelegg Formation: a new stratigraphic scheme for the Early Jurassic of northern Switzerland

Reisdorf, Achim G.; Wetzel, Andreas; Schlatter, Rudolf; Jordan, P.M.

doi:10.1007/s00015-011-0057-1

Cited by 31 publications

(31 citation statements)

References 24 publications

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“…Schaeren and Norbert (1989) and Blaesi et al (1991) defined the base of the Opalinus Clay as a lithological transition of argillaceous sediments to more marly sediments. The latter have been identified as the Gross Wolf Member of the Staffelegg Formation (Reisdorf et al 2011;Hostettler et al 2017). The upper boundary of the Opalinus Clay is defined by a distinct hardground of chamositic crusts (Blaesi et al 1991) and iron oolites.…”

Section: Lithofaciesmentioning

confidence: 99%

Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments

Bossart¹,

et al. 2017

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Geologic repositories for radioactive waste are designed as multi-barrier disposal systems that perform a number of functions including the long-term isolation and containment of waste from the human environment, and the attenuation of radionuclides released to the subsurface. The rock laboratory at Mont Terri (canton Jura, Switzerland) in the Opalinus Clay plays an important role in the development of such repositories. The experimental results gained in the last 20 years are used to study the possible evolution of a repository and investigate processes closely related to the safety functions of a repository hosted in a clay rock. At the same time, these experiments have increased our general knowledge of the complex behaviour of argillaceous formations in response to coupled hydrological, mechanical, thermal, chemical, and biological processes. After presenting the geological setting in and around the Mont Terri rock laboratory and an overview of the mineralogy and key properties of the Opalinus Clay, we give a brief overview of the key experiments that are described in more detail in the following research papers to this Special Issue of the Swiss Journal of Geosciences. These experiments aim to characterise the Opalinus Clay and estimate safetyrelevant parameters, test procedures, and technologies for repository construction and waste emplacement. Other aspects covered are: bentonite buffer emplacement, highpH concrete-clay interaction experiments, anaerobic steel corrosion with hydrogen formation, depletion of hydrogen by microbial activity, and finally, release of radionuclides Geosci (2017) 110:3-22 DOI 10.1007 into the bentonite buffer and the Opalinus Clay barrier. In the case of a spent fuel/high-level waste repository, the time considered in performance assessment for repository evolution is generally 1 million years, starting with a transient phase over the first 10,000 years and followed by an equilibrium phase. Experiments dealing with initial conditions, construction, and waste emplacement do not require the extrapolation of their results over such long timescales. However, experiments like radionuclide transport in the clay barrier have to rely on understanding longterm mechanistic processes together with estimating safety-relevant parameters. The research at Mont Terri carried out in the last 20 years provides valuable information on repository evolution and strong arguments for a sound safety case for a repository in argillaceous formations.

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Section: Lithofaciesmentioning

confidence: 99%

Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments

Bossart¹,

et al. 2017

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“…2). During the Early Jurassic, a fully marine environment with successively increasing water depth developed, leading to the formation of calcareous, marly, and argillaceous rocks denoted as the Staffelegg Formation (Reisdorf et al 2011). Together with rocks of the Keuper, these rocks form the core of the Mont Terri anticline.…”

Section: Litho-and Mechanical Stratigraphymentioning

confidence: 99%

Tectonic evolution around the Mont Terri rock laboratory, northwestern Swiss Jura: constraints from kinematic forward modelling

Nussbaum¹,

Kloppenburg²,

Caër

et al. 2017

Swiss J Geosci

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We propose a geometrically, kinematically, and mechanically viable thin-skinned kinematic forward model for a cross section intersecting the Mont Terri rock laboratory in the frontal-most part of the Jura fold-and-thrust belt, Switzerland. In addition to the available tunnel, borehole, and surface data, initial boundary conditions are crucial constraints for the forward modelling scenarios, especially the inherited topography of the basement and any pre-compressional offset within the Mesozoic sediments. Our kinematic analysis suggests an early-stage formation of the Mont Terri anticline located above ENE-trending, Late Paleozoic extensional faults, followed by back-stepping of the deformation developing the Clos du Doubs and Caquerelle anticlines further south. In this model, the thrust sequence was dictated by the inherited basement faults, which acted as nuclei for the ramps, detached along the basal décollement within the Triassic evaporites. The mechanical viability of both the thrust angles and thrust sequence was demonstrated by applying the limit analysis theory. Despite numerous subsurface geological data, extrapolation of structures to depth remains largely under-constrained. We have tested an alternative model for the same cross section, involving an upper detachment at the top of the Staffelegg Formation that leads to duplication of the sub-Opalinus Clay formations, prior to detachment and thrusting on the Triassic evaporites. This model is geometrically and kinematically viable, but raises mechanical questions. A total displacement of 2.9 and 14.2 km are inferred for the classical and the alternative scenarios, respectively. In the latter, forward modelling implies that material was transported 10.8 km along the upper detachment. It is not yet clear where this shortening might have been accommodated. Despite the differences in structural style, both models show that pre-existing basement structures might have interfered in time and space. Both styles may have played a role, with lateral variation dictated by basement inherited structures.

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“…In contrast to the table of the most important outcrops of the Staffelegg-area published by Amsler (1919), Early Hettangian strata do occur west of the Staffelegg (see Heer, 1865: 92;Erni, 1910: 43;Jordan, 1983;Wetzel et al, 1993). A nearly complete Early Jurassic section was exposed approximately 3 km east of the Staffelegg-Pass at ''Buessge'' (Jordan, 1983;Reisdorf et al, 2011). This section represents the type-locality of the Staffelegg Formation substituting the previously used informal stratigraphic unit ''Lias'' for the Early Jurassic (Reisdorf et al, 2011).…”

Section: Geological Settingmentioning

confidence: 99%

“…A nearly complete Early Jurassic section was exposed approximately 3 km east of the Staffelegg-Pass at ''Buessge'' (Jordan, 1983;Reisdorf et al, 2011). This section represents the type-locality of the Staffelegg Formation substituting the previously used informal stratigraphic unit ''Lias'' for the Early Jurassic (Reisdorf et al, 2011).…”

Section: Geological Settingmentioning

confidence: 99%

“…This limestone belongs to the Breitenmatt Member and is Early Pliensbachian in age (previously ''Kondensiertes Pliensbachien'' after Jordan, 1983). According to Reisdorf et al, (2011), the Breitenmatt Member is represented in the Folded Jura by a thin interval of limey marls and phosphoritic nodular limestones rich in macrofossils.…”

Section: Breitenmatt Member and Müsenegg Bedmentioning

confidence: 99%

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First record of the leptonectid ichthyosaur Eurhinosaurus longirostris from the Early Jurassic of Switzerland and its stratigraphic framework

2011

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The Staffelegg Formation: a new stratigraphic scheme for the Early Jurassic of northern Switzerland

Cited by 31 publications

References 24 publications

Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments

Mont Terri rock laboratory, 20 years of research: introduction, site characteristics and overview of experiments

Tectonic evolution around the Mont Terri rock laboratory, northwestern Swiss Jura: constraints from kinematic forward modelling

First record of the leptonectid ichthyosaur Eurhinosaurus longirostris from the Early Jurassic of Switzerland and its stratigraphic framework

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